The challenge is to lay the groundwork for OTL East Karelia and the Kola Peninsula to become part of a post-WW1 independent Finland.
The PODs can range from one of the Russo-Swedish Wars up to the end of a post-WW1 Russian Civil War*, yet with the proviso of Russia still retaining St. Petersburg and Arkhangelsk with ATL Severodvinsk playing a similar role to OTL Murmansk (along with any other OTL settlement in the Arkhangelsk Oblast being further expanded).
* - Essentially WW1 roughly ends as it did in OTL yet the Western Allies decide early on to back the Finns in the region as a counter weight to the Red Army in tandem with the Russian Civil War continuing a bit longer to leave the Reds in a much weaker position for the Finns to move into the region (with Sweden or an ATL United Scandinavia providing much more backing - likely motivated to do so in order to use an expanded ATL Finland as a buffer state kind of like OTL Russia does with Belerus).
The PODs can range from one of the Russo-Swedish Wars up to the end of a post-WW1 Russian Civil War*, yet with the proviso of Russia still retaining St. Petersburg and Arkhangelsk with ATL Severodvinsk playing a similar role to OTL Murmansk (along with any other OTL settlement in the Arkhangelsk Oblast being further expanded).
* - Essentially WW1 roughly ends as it did in OTL yet the Western Allies decide early on to back the Finns in the region as a counter weight to the Red Army in tandem with the Russian Civil War continuing a bit longer to leave the Reds in a much weaker position for the Finns to move into the region (with Sweden or an ATL United Scandinavia providing much more backing - likely motivated to do so in order to use an expanded ATL Finland as a buffer state kind of like OTL Russia does with Belerus).